EP0310783B1 - Verfahren zur Stabilisierung der Ausgangsfrequenz eines spannungsgesteuerten Oszillators sowie Oszillator- und Sensoreinrichtung, die nach dem Verfahren arbeitet - Google Patents

Verfahren zur Stabilisierung der Ausgangsfrequenz eines spannungsgesteuerten Oszillators sowie Oszillator- und Sensoreinrichtung, die nach dem Verfahren arbeitet Download PDF

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Publication number
EP0310783B1
EP0310783B1 EP88112827A EP88112827A EP0310783B1 EP 0310783 B1 EP0310783 B1 EP 0310783B1 EP 88112827 A EP88112827 A EP 88112827A EP 88112827 A EP88112827 A EP 88112827A EP 0310783 B1 EP0310783 B1 EP 0310783B1
Authority
EP
European Patent Office
Prior art keywords
voltage
frequency
signal
output
oscillator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88112827A
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German (de)
English (en)
French (fr)
Other versions
EP0310783A3 (en
EP0310783A2 (de
Inventor
Helmut Dipl.- Ing. Vemmer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Peter Lancier Maschinenbau-Hafenhuette & Co KG GmbH
Original Assignee
Peter Lancier Maschinenbau-Hafenhuette & Co KG GmbH
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Publication of EP0310783A2 publication Critical patent/EP0310783A2/de
Publication of EP0310783A3 publication Critical patent/EP0310783A3/de
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Publication of EP0310783B1 publication Critical patent/EP0310783B1/de
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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C3/00—Angle modulation
    • H03C3/02—Details
    • H03C3/09—Modifications of modulator for regulating the mean frequency
    • H03C3/0908—Modifications of modulator for regulating the mean frequency using a phase locked loop
    • H03C3/095—Modifications of modulator for regulating the mean frequency using a phase locked loop applying frequency modulation to the loop in front of the voltage controlled oscillator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/085—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal
    • H03L7/097—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal using a comparator for comparing the voltages obtained from two frequency to voltage converters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C2200/00—Indexing scheme relating to details of modulators or modulation methods covered by H03C
    • H03C2200/0004—Circuit elements of modulators
    • H03C2200/0029—Memory circuits, e.g. ROMs, RAMs, EPROMs, latches, shift registers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C2200/00—Indexing scheme relating to details of modulators or modulation methods covered by H03C
    • H03C2200/0037—Functional aspects of modulators
    • H03C2200/0045—Pulse width, duty cycle or on/off ratio

Definitions

  • the invention is based on a method for stabilizing the output frequency f v of a voltage-controlled oscillator according to the preamble of claim 1 and also comprises a voltage-controlled oscillator device (VCO) for carrying out the method and a sensor device.
  • VCO voltage-controlled oscillator device
  • VCOs Voltage controlled oscillators
  • U / F converters are devices for converting direct voltages into frequencies proportional to them for measuring or transmission purposes.
  • Precise, voltage-controlled oscillators are also known - cf. e.g. B. ELEKTOR, 1977, 5-51 - which, for example, only have a linearity error of 0.5% and a temperature drift of 0.01% / ° C according to the aforementioned literature.
  • RCA-CA 3130 which works as a multivibrator and generates rectangular pulses
  • a sequence of rectangular pulses results as an output signal.
  • the output voltage of the multivibrator is fed via an integrating element to a non-inverting input of a second integrated circuit, which works as a comparator.
  • the output of the comparator is again connected to the inverting input of the multivibrator.
  • the voltage is set precisely by the feedback.
  • Oscillators of the aforementioned type can be stabilized more precisely by complex switching measures.
  • these switching measures require additional components that further significantly increase the relatively high power consumption of the aforementioned oscillators.
  • the known circuits are therefore less suitable, in particular for monitoring telecommunication cables with remote measuring points.
  • VCO voltage-controlled oscillator
  • VCO voltage-controlled oscillators
  • the features specified in claims 7 and 8 are advantageously used in a sensor device.
  • the invention accordingly comprises a precise U / F converter which is implemented with a quartz-controlled area integral of the control voltage.
  • the design of the circuit shows that it works in the microampere range to save energy and can be implemented using CMOS technology.
  • phase lock circuit PLL
  • the phase lock circuit works as a proportional controller with respect to the phase.
  • the control loop condition applies that the phase deviation ( ⁇ 1 - ⁇ 0) is proportional to the reciprocal of the gain triggered by the control loop.
  • a direct voltage U v is compared with a direct voltage U r , the direct voltage U v being the sensor signal and the direct voltage U r being a control voltage which is proportional to the output frequency of the U / F converter.
  • U r is formed from the area integral of a pulse sequence, the pulse length t r being a constant, quartz-controlled time.
  • the frequency of the pulse train is closely related to the frequency of the U / F converter.
  • the linearity of the U / F converter is therefore only dependent on the stability of the quartz control signal.
  • the way via the voltage-frequency converter described has the advantage that an existing quartz clock frequency of a time-division multiplex control of the sensor can be used for the regulation.
  • a PLL does not offer this possibility of stabilization either.
  • a PLL can only depend on the phase position of the input signal and in this case the input signal is a pure DC voltage.
  • a voltage-controlled oscillator of the type described above is installed in particular in an addressable sensor transmitter.
  • These are so-called intelligent sensors which sense physical measured variables, such as ambient pressure, temperature, air humidity and the like, and generate electrical signals which correspond to the measured value of the physical measured variable.
  • the electrical signals ie certain Voltages are converted into frequency-modulated electrical signals with the help of a voltage-controlled oscillator.
  • These signals can then be transmitted up to 200 km over wire lines without intermediate amplification. This is generally, for. B. in cable monitoring devices, only a copper twin wire available.
  • the sensors must therefore be connected in parallel.
  • a time-sequential multiplexing method is used to query and control the measuring circuit, and in general up to 127 sensors can be connected.
  • the copper twin wire provides both the energy supply for all sensors and the time-sequential signal transmission from each individual sensor.
  • the sensors In order for the sensors to send them sequentially according to the addressing, the sensors must be synchronized with one another. The synchronization takes place when the operating voltage is applied to the line.
  • Each monitoring unit therefore generally has a quartz-controlled clock generator with a frequency of 32.728 kHz as the clock standard.
  • this means that the clock standard is also available for other purposes in which a reference frequency f r is required. It is therefore particularly advantageous to use the aforementioned method in sensor devices which have such a quartz-controlled frequency standard.
  • the output frequency f v of the voltage controlled oscillator is set so that it is generally between 11 and 34 kHz, where f v is the frequency output directly at the output of the oscillator.
  • f e is the frequency output directly at the output of the oscillator.
  • f e is the frequency output directly at the output of the oscillator.
  • ⁇ a circuit-dependent time constant
  • FIG. 1 shows a schematic block diagram of an addressable sensor device, such as is used in particular in the pressure monitoring of long-distance lines.
  • a sensor 1 which is set up for pressure monitoring, generates an electrical signal that corresponds to the relevant physical quantity.
  • the signal obtained is amplified via a measuring amplifier 2 and input to an input 3 of a U / F converter device 4 by means of a voltage-controlled oscillator (framed with a -.-).
  • the input measuring voltage is designated U v .
  • the voltage U v reaches the plus (+) input of an integrator 5, to which a control voltage U r is input at the minus (-) input, the generation of which will be explained below.
  • the integrator 5 generates an output signal according to the formula
  • the output of the integrator 5 is connected via a line to a voltage-controlled oscillator (VCO) 6.
  • VCO voltage-controlled oscillator
  • the voltage-controlled oscillator 6 Depending on the input voltage U d, the voltage-controlled oscillator 6 generates an output signal "A" with the output frequency f v in the form of square-wave pulses.
  • the frequency f v in the present exemplary embodiment is usually in the range between 11.2 to 33.6 kHz.
  • the output frequency f v in a non-stabilized voltage-controlled oscillator 6 is generally not proportional to the measurement voltage U v . A regulation is therefore necessary.
  • the voltage-controlled oscillator 6 is followed by a 4-bit divider 7, the outputs of which can be taken at different, frequency-divided frequencies.
  • a signal B of the frequency f v / 4 controls a sequential switch or gate switch 9.
  • the switch 9 also receives a constantly frequent reference signal D of the frequency f r via a line 11, which is emitted by a quartz-controlled frequency standard 10 becomes.
  • the square-wave signal pulses generated by the gate switch 9 result in a signal sequence "C" which is applied to a low-pass filter 12.
  • the low-pass filter 12 generates the control voltage U r already mentioned, which is applied to the minus (-) input of the integrator 5.
  • the switch 9 With a rising edge of the signal "B”, the switch 9 is switched to ONE, ie a flip-flop circuit switches to a first state. That state ends as soon as the signal “D" of a rising and a falling edge has come in from the quartz standard 10.
  • the signal “C” is set when the signal “D” rises and the switch 9 is simultaneously set to ONE.
  • Signal “C” is reset when a new rising edge appears at signal "D”. At this point the switch has already left the ONE state.
  • the signal “C” has a duration of 1 / f r .
  • the pause time t p results from the time between the descent and the ascent edge at signal "C".
  • the f at the variable rate are not constant but vary with the frequency f v.
  • the frequency f r of the quartz standard 10 with 32.728 kHz can also be replaced by another reference frequency. Higher frequencies can be discovered by corresponding, known divider circuits. However, the embodiment described here produces particularly advantageous integration signals.
  • the 4-bit divider 7 is also followed by an 8-bit shift register 14, which is no longer part of the actual oscillator device, which shifts the incoming signals in a certain way and at the same time gives up a summing resistance network 15, a stepped sine signal being generated in the process, which is sent through a filter 16 for smoothing.
  • a sinusoidal signal with a voltage corresponding to the measured value voltage then results.
  • the sinusoidal shape can be created relatively easily since there is an output frequency f v and this can be divided in a simple manner in the existing 4-bit divider 7. No additional parts are required.
  • An 8-bit shift register 14 is clocked via a line 19, with which the signal f e is in each case with a sixteenth the frequency is shifted in cycles.
  • a staircase shape is generated in which the individual inputs are changed with different resistors in accordance with the defined sinusoidal contour. This always gives the same amplitude for the sinusoidal shape at different frequencies, which is dependent on f v .
  • a time-division multiplex controller 17 is provided, which is also precisely controlled by the frequency standard 10. Appropriate addressing ensures that each sensor device emits its signal at a specific time.
  • FIG. 1 The function of the addressable sensor transmitter device shown in FIG. 1 is explained in detail as follows, reference also being made to FIGS. 2 and 3.
  • the voltage-controlled oscillator 6 Depending on the voltage U v from the integrator 5, the voltage-controlled oscillator 6 generates a square-wave output signal of the frequency f v in the range between 11.2 to 33.6 kHz. These values have proven to be favorable, since generally inexpensive clock frequency standards with a frequency of 32.728 kHz are available.
  • the output frequency f v is usually not exactly proportional to the voltage applied unless the method described below is used.
  • the aim of the present method is to have the linear change in the output frequency f v exactly follow the applied measuring voltage U v .
  • Number 1 of FIG. 2 shows the output frequency f v of the oscillator 6.
  • the frequency f v is divided down to such an extent that it only has 1/16 of the desired output frequency, ie in the range of approximately 0, 7 to 2.1 kHz.
  • This frequency corresponds to the output frequency of the overall sensor circuit.
  • a reference voltage U r is required parallel to the voltage U v at the input of the integrator 5 and is available at the output of the low-pass filter 12. This voltage is obtained from a sequence of square-wave pulses which are supplied to the low-pass filter 12 by a quartz-controlled circuit 10 in the gate switch 9.
  • t r 1 / f r .
  • Their length is quartz stable and completely independent of the frequency f v .
  • the signal sequence C can be sent, for example, via the low-pass filter 12 and can thus be integrated, with its total area being added up.
  • the resulting integration voltage U r is a quartz-controlled reference voltage, the change of which is absolutely linear with the frequency f v .
  • the difference-forming integrator 5 now receives both the original measurement voltage U v and the reference voltage U r . According to the circuit of the integrator 5, these voltages are subtracted from one another. If the measurement signal voltage U v is greater than the reference voltage U r , the integrator output voltage slowly rises. If the measurement signal voltage U v is less than the reference voltage U r , the integrator voltage runs downwards.
  • a control voltage U d is available at the output of the integrator 5, which controls the voltage-controlled oscillator 6.
  • the control voltage now controls the oscillator upwards or downwards until the reference voltage at the input of the integrator is absolutely equal to the measurement input voltage U r . If the tie is reached, the integrator is neither controlled positively nor negatively, ie its control output voltage is constant. Its frequency no longer changes.
  • the integrated voltage U r also changes .
  • the integrator 5 thus generates a changed input voltage U v , which regulates the voltage-controlled oscillator back against the undesired migration until it has the exact value the measuring voltage has reached. This creates a closed control loop in which the output voltage of the oscillator is no longer dependent on its stability, but only on the accuracy of the frequency standard 10.
  • the precisely controlled output frequency f v which has been sent via the 4-bit divider 7, can be converted into a sine signal of the same frequency via a digitally generated stepped sine signal.
  • the conversion takes place in the 8-bit shift register 14 with a resistor network connected downstream (cf. FIG. 2).
  • the resistor network 15 is graded so that the interconnected signals generate a step-shaped sinusoidal signal when controlled by the shift register (see FIG. 2).
  • This signal is sent through the filter 16, at the output of which a pure sine signal is available.
  • This pure sine signal is thus available as an impressed voltage.
  • a sinusoidal signal with impressed current is converted in a subsequent voltage-current converter (reference number 18).
  • control and signal retrieval is carried out via a known time-multiplex controller 17. It should be noted that the current consumption is constant, so that only the sinusoidal current of the U / I converter is superimposed on the rest of the direct current as modulation alternating current. This impressed modulation current can be evaluated as a useful transmission signal at the remote receiver input.
  • the time-multiplex control ensures sequential control, the control resulting in a time window of 2 s each, in which time the modulation of the corresponding sensor (700 Hz to 2100 Hz) is switched on for 1.5 s.
  • the invention is particularly applied to sensor circuits. It therefore relates in particular to a sensor switching device which makes use of the aforementioned U / F conversion by means of a voltage-controlled oscillator (VCO).
  • VCO voltage-controlled oscillator

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  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
EP88112827A 1987-08-07 1988-08-06 Verfahren zur Stabilisierung der Ausgangsfrequenz eines spannungsgesteuerten Oszillators sowie Oszillator- und Sensoreinrichtung, die nach dem Verfahren arbeitet Expired - Lifetime EP0310783B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3726224 1987-08-07
DE19873726224 DE3726224A1 (de) 1987-08-07 1987-08-07 Verfahren zur stabilisierung der ausgangsfrequenz eines spannungsgesteuerten oszillators sowie oszillator- und sensoreinrichtung, die nach dem verfahren arbeitet

Publications (3)

Publication Number Publication Date
EP0310783A2 EP0310783A2 (de) 1989-04-12
EP0310783A3 EP0310783A3 (en) 1990-08-08
EP0310783B1 true EP0310783B1 (de) 1995-02-22

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EP88112827A Expired - Lifetime EP0310783B1 (de) 1987-08-07 1988-08-06 Verfahren zur Stabilisierung der Ausgangsfrequenz eines spannungsgesteuerten Oszillators sowie Oszillator- und Sensoreinrichtung, die nach dem Verfahren arbeitet

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EP (1) EP0310783B1 (enrdf_load_stackoverflow)
DE (1) DE3726224A1 (enrdf_load_stackoverflow)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19953578A1 (de) 1999-11-08 2001-05-23 Mikron Ag Fuer Integrierte Mik Vorrichtung und Verfahren zur Erzeugung eines Taktsignals
DE10201083B4 (de) * 2002-01-14 2004-05-13 Lerner, Zinoviy, Dipl.-Ing. Der Frequenzgeber
DE102005041759A1 (de) 2005-09-02 2007-09-06 Pepperl + Fuchs Gmbh Oszillatorschaltung sowie Verfahren zur Beeinflussung, Steuerung oder Regelung der Frequenz eines Oszillators

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2160863B2 (de) * 1971-12-08 1975-11-27 Honeywell Gmbh Schaltungsanordnung zum Erzeugen von Sinusschwingungen durch Summieren mehrerer gleichfrequenter Rechteckschwingungen
CH539978A (de) * 1972-05-24 1973-07-31 Wirth Gallo & Co Vorrichtung zur Regelung von Frequenz und Phase eines Oszillators
US4387351A (en) * 1980-12-18 1983-06-07 Motorola Inc. Wideband FM modulator and AFC control loop therefor

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Publication number Publication date
DE3726224C2 (enrdf_load_stackoverflow) 1990-10-11
EP0310783A3 (en) 1990-08-08
EP0310783A2 (de) 1989-04-12
DE3726224A1 (de) 1989-02-16

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